So 6 weeks in to owning my printer and with a moderate amount of printing I started noticing a horrid smell coming from the printer. It was a mix between melting plastic and garbage. I’d been printing with ABS filament from 3dprinted.co and had printed a couple hundred grams worth.

Even though I’ve read ABS can sometimes smell bad I hadn’t noticed any bad smell coming from my 3dprinted.co filament.  At first I thought maybe the smell could have been the filament. But it kept getting stronger and stronger to the point where I had to stop printing altogether.

I checked the side of the control box and found the smell was coming from there. After opening it up I could clearly see one of the ground wires, where the power supply connects to the Melzi board, was burnt and melted. This is apparently a common issue with v1.0 Melzi boards and is an issue with the power connectors pcb traces being too small to take the current coming from the power supply.

They heat up the pcb and the connector’s metal internals which then heats the connected wires to the point where the plastic melts and the copper wires harden and become brittle.

I emailed Balco and got a reply from WinPlus support. After providing proof of purchase they offered me two solutions. Either they send out a replacement Melzi board or organise repair of the printer. I went with the replacement board option and received the board in 3 days.

Here’s the new board where you can see a different style of connector for the power and hotbed connections. I hope that this board can better handle the current. Luckily the damage to the power supply’s ground wire was only 3cm so I was able to cut the melted part off and reattach the cable to the new board.

Both the power and hotbed connects have a screw in style mount which I read in other online articles is supposed to be the standard when taking a 12v current. I stripped the wires for the power supply’s positive and ground then screwed them down in the connector. Since there was no damage to my hotbed wires I didn’t need to strip the wire for them.

I connected each of the other connectors one at a time to make sure I didn’t mix any up. I always take a photo of something before I disassemble it just in case I forget something or need it as reference in the future.

Here’s everything reattached to the new board:

I also took a photo of the back of the power supply just in case anyone is curious.

After assembling the parts back in the control box I fired it up and did a 6 hour test print. No smell anymore! Hopefully I shouldn’t have this issue again but it’s good to know Balco’s WinPlus support are super fast to help.